The present invention relates to a hydraulic actuating device for a device having a first and a second hydraulically moveable component. This actuating device comprises a first and a second hydraulic actuator, respectively for moving the first and second moveable components. The first and second actuators each have a housing in which there is a space in which a piston/piston rod assembly can move in a reciprocating manner, with a piston and a piston rod which is coupled to the piston and projects out of the housing, the piston delimiting a first working chamber and a second working chamber in the housing. The housing is provided with a first and a second connection, which are respectively in communication with the first and second working chambers in order to supply and discharge hydraulic fluid in order to displace the piston/piston rod assembly. The actuating device further comprises a connecting line which forms an open connection between the second working chamber of the first actuator and the first working chamber of the second actuator. The actuating device also comprises a pump having a delivery port and a suction port, a reservoir for hydraulic fluid, the suction port of the pump being connected to the reservoir, and valve means, having one or more actuable valves.
In practice, it is often the case that a mechanical device has a plurality of moveable components which are each coupled to an associated hydraulic actuator in order to drive the component in question. The movement of each component often forms part of a sequence of movements of the device, i.e. a combination of successive and/or (partially) simultaneous movements of the components of the device.
FIG. 1 of the present application shows a vehicle having a generally known design, which is shown by way of example, of a hydraulically actuable convertible-top assembly. This convertible-top assembly comprises a plurality of moveable components, which are each moved by an associated hydraulic actuator or by a pair of actuators connected in parallel on either side of the body. By way of example, a pair of main bow actuators, a pair of rear bow actuators, a pair of actuators for the tonneau cover, and optionally hydraulic actuators of the locking means for the convertible top and/or the tonneau cover are provided. A convertible-top assembly of this type undergoes an xe2x80x9copening movement sequencexe2x80x9d, during which the convertible top is opened, and a xe2x80x9cclosing movement sequencexe2x80x9d, in which the convertible top is closed.
There is a commercial demand for the sequences of movements of a convertible-top assembly of this type to be carried out quickly, with time savings of a few seconds being deemed relevant. There is also a desire for the sequences of movements to be graceful and for the movements of the components, in particular of the convertible top and the tonneau cover, to proceed smoothly.
In a known embodiment of the hydraulic actuating device belonging to the convertible-top assembly, there is provision for all the movements of the components to take place sequentially, so that a movement of one component is entirely completed before another component is set in motion. This has the advantage that simple limit-position switches can be used in order to detect that a limit position of an actuator has been reached. Furthermore, this avoids any possible conflict between movements which coincide, for example the possibility of the tonneau cover not having opened sufficiently to allow the convertible top past. However, a drawback is that a sequence of movements takes a considerable time and also looks jerky.
It is known from the prior art in the field of actuable convertible-top assemblies to solve the problem described above by using electromechanical actuators for the components instead of hydraulic actuators. In this case, position sensors are provided, which detect the position of the actuators and/or the components of the convertible-top assembly which are coupled thereto over the entire movement path (or a part thereof). It is then possible, for example, for the position of the tonneau cover to be continuously detected during a sequence of movements and for the movement of the convertible top to be made to partially coincide with the movement of the tonneau cover. However, electromechanical actuators of this type with associated position sensors and control electronics are expensive and susceptible to faults.
It is an object of the present invention to propose an alternative hydraulic actuating device.
The invention achieves this object by providing a hydraulic actuating device for a device having a first and a second hydraulically moveable component as abovedescribed wherein the valve means are designed to optionally: connect the first connection of the first actuator to the reservoir, or connect the delivery port of the pump to the first connection of the first actuator, wherein the valve means are also designed to optionally: connect the second connection of the second actuator to the reservoir, or connect the delivery port of the pump to the second connection of the second actuator, and wherein the valve means are also designed to optionally: connect the connecting line to the reservoir, or connect the delivery port of the pump to the connecting line, or make the connecting line with the connected second chamber of the first actuator and the first chamber of the second actuator into a closed volume.
This actuating device makes it possible to make the connecting line with the connected second chamber of the first actuator and the first chamber of the second actuator into a closed volume, resulting in a state in which the first and second actuators are connected in series. In this state, the first and second actuators move synchronously, with a fixed ratio between the speeds of movement, the fixed ratio being determined by the dimensioning of the actuators.
The actuating device also allows the first and second actuators to be driven independently of one another, so that, in an advantageous embodiment, it is possible, for example, for the first actuator to be in operation throughout the sequence of movements, then for the first and second actuators to be connected in series and therefore move synchronously, and then finally for the second actuator to continue its movement while the first actuator is retained in a limit position.
In particular, the invention provides for an actuating device of this type to be used to drive various components of a convertible-top assembly of a motor vehicle. By way of example, the first actuator moves the main bow of the convertible top and the second actuator moves the tonneau cover. In another example, for what is known as a retractable hard top, the first actuator moves a first panel and the second actuator moves a second panel of the hard top.
It will be clear to the person skilled in the art that the hydraulic actuating device is also suitable for other applications.
Furthermore, it will be clear to the person skilled in the art that the inventive idea can also be applied to more than two actuators.
The inventive idea and an advantageous embodiment of the hydraulic actuating device according to the invention are described in the following description with reference to the drawings.